Corneal clamp



March 22, 1960 G. A. STEWART CORNEAL CLAMP Filed July 3, 1958 lfzg. 2.

JJ v

United States Patent CORNEAL CLAMP Gene A. Stewart, Washington, D.C.

Application July 3, 1958, Serial No. 7 46,569

3 Claims. (Cl. 248-361) (Granted under Title 35, U.S. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment of any royalty thereon.

The operation of keratoplasty frequently has been limited by the unavailability of donor corneal material, and for obviating such unavailability, many attempts have been made to store corneal grafts over long periods, and various methods for such storage of donor corneal materials have been undertaken but without success. Such attempts have included rapid freezing in liquid nitrogen with and without isopentane as an intermediate heattransfer medium. See, in this connection, papers by H. M. Katzin: Preservation of Corneal Tissue by Freezing and Dehydration, Am. J. Ophth. 30: 1128 (1947); I. H.

Leopold and F. H. Adler: Use of Frozen-Dried Cornea as Transplant Material, Arch. Ophth. 37: 268 (1947); G. H. Smelser and V. Ozanics: Eiect of Quick Freezing at Various Temperatures of Donor Tissues in Corneal Transplants, Proc. Soc. Exper. Biol. and Med. 62: 274- 277 (1946). In the method described in the rst two of the foregoing papers, the grafts, after freezing, were dried in vacuo over phosphorus pentoxide at 40 C. They were reconstituted before use, in most cases, by the addition of isotonic sodium chloride solution. In the paper by Smelser and Ozanics, the materials were not dried, but were stored at 195 C. for periods of from one hour up to tive days. The grafts then were rapidly thawed by immersion in isotonic sodium chloride solution at 39 C. When thus prepared for implantation, both the frozen and the freeze-dried grafts were clear and of normal consistency. A great majority of these grafts healed well after implantation, but in most of them translucency was lost within the rst three weeks. There was no lasting transparency in any of the grafts during the time that they were observed.

In 1949, Polge and associates found that fowl spermatozoa treated with glycerin-saline solution retained their motility after freezing and thawing (C. Polge, A. U. Smith, and A. S. Parkes: Revival of Spermatazoa After Vitriication and Dehydration at Low Temperature, Nature, London 164: 666, 1949). Since that time, marked success has been reported on the survival of skin, blood, and endocrine tissue treated in a similar manner (A. U. Smith and A. S. Parkes: Preservation of Ovarian Tissue at Low Temperature, Lancet 2: 570, 1951). In early 1954, Eastcott and his colleagues reported that human corneas treated in this way and stored at 79 C. yielded lamellar grafts that diiered in no way from fresh grafts in their final result and transparency (H. H. G. Eastcott, A. G. Cross, A. G. Leigh, and D. P. North: Preservation of Corneal Grafts by Freezing, Lancet l: 237, 1954). v

Since success had been obtained inrpreserving corneas by using the glycerin-saline technique with freezing, there was considered the possibility of carrying the process one step further and drying the tissue in a vacuum. This l consisted essentially of drying corneas by removing the water from the glycerin solution (J. N. McNair and J. H.

2,929,6@3 "Patented Mar. 22, 1960 ice King, Ir.: Preservation of Cornea by Dehydration, A.M.A. Archives of Ophthalmology 53: 519-521, 1955).

This new system used to preserve donor cornea by dehydration has brought about one of the greatest advances in Ophthalmology since the iirst fresh corneal transplant was effected. Now it is possible to store donor corneas indefinitely and stockpile them for future use. However, it has been observed that when donor corneas which have been preserved in this manner are removed from their storage containers, the cornea have a tendency to wrinkle, and also during the process of dehydration, the donor corneas sometimes roll up or fold with resulting creases such as a piece of paper would have after being folded. Additionally, in view of the opaqueness of the donor corneas, their visibility in the preserving and dehydrating liquid, which usually is substantially anhydrous glycerin, may be reduced to the point where difficulty is experienced in locating the cornea for removal thereof from the preserving and dehydrating liquid. When dehydrated donor corneas which do not roll up or fold are rehydrated, they have smooth surfaces, whereas those that have folded are ridged where the folds have occurred, and the presence of such ridges makes it very difcult to remove a lamellar graft from the cornea and maintain the graft at the same thickness throughout.

The customary present practice is to provide a hemispherical mounting for the cornea, which mounting is composed of a suitable moldable plastic material, to which mounting the cornea is secured by pins, the mounting with the cornea thus secured being buried in a body of sterile paraffin contained in a Petri dish, while in the case of dehydrated cornea, the cornea for the transplant is suspended free in the preserving and dehydrating liquid contained in a test tube, and because the cornea is opaque it is diicult to see and to secure. `However, in accordance with the instant invention, there is provided a corneal clamp composed of suitable plastic material for use in keratoplasty when trephining the donor or dehydrated cornea, which clamp includes a simple locking device to hold the cornea in a secure position with a table for use of the trephine. The cornea is dehydrated in a test tube and opened 'in the operating room as needed. A plastic slab which receives the locking device remains in the operating room. If the table for the locking device is marred by cutting action of the trephine, the device can be disposed of, as its cost is negligible.

The present invention therefore provides a simple mechanical clamp construction for receiving and maintaining corneas which are being preserved by a standard dehydration technique free from deformations such as the aforesaid wrinkling and folding during the dehydration, while providing for drainage of moisture from the endothelium f side of the cornea during dehydration thereof.

Further objects and advantages of the present construction will become apparent as the description proceeds and the features of novelty will be pointed out in particularity in the appended claims.

The structural details and features of the corneal clamp of the present invention are shown in the accompanying drawings, in which- Fig. 1 is a plan View of a locking unit employed in the present invention;

Fig. 2 is a plan view of a hemispherical corneal mounting unit employed in conjunction with the locking unit shown in Fig. 1;

Fig. 3 is a vertical section of the mounting device of Fig. 2;

Fig..4 is a plan view of the complete clamping assembly with the locklng device of Fig. 1 and the corneal mounting of Figs. 2 and 3 in position on a mounting plate therefor provided with oppositely disposed locking f lugs, the arrows indicating the direction of rotation o p the locking element of Fig. 1 for manipulating the same Y 'to bring it into secured position on the mounting plate;

Fig. 5 is a plan view of the assembly of Fig. 4, but showing the parts turned with respect to the'locking Vplateso as to be secured thereby;Y

5 and 6, showing the clamping assembly positionedlonV an operating Ytable surface; and

Fig. 8V is a sectional view vtaken'on the line 8- 8 Vof `Fig. 7, looking in the direction of the arrows.Y

Referring more particularly tothe drawings',- the corne clamp construction of the present invention comprises an assembly of separable partys or units including a locking unitl 10 hav-ing a generally circular center openfl ing-12, the periphery of which is. provided with opposite, inwardly projee'tingtongues 14 having beveled ends 16 which are adaptedlto receive a substantially hemispherical cornea`mountin-g 18, the upper surface of which is adapted to receive a cornea 29 that is to be preserved in a manner noted above for graft purposes,'the;rnount ing 18 being slipped into the opening 12 of the locking unit 10 until the beveled ends 16 fof the opposite locking tongues 14 engage and lockingly interht with a cornea 28j thereby securing the cornea 2o rigidly'on its mounting 18 freefrom folds or wrinkles or other'surface deformations. The :dat undersurface of the VVhernispherical mounting 18 is recessedas is indicated at 22 for a purpose to be noted hereinafter.` Y f The locking unit 10 is provided with oppositelydirected locking lingers 24 adapted to slip under opposite angular upstanding locking lugs Z6 provided on a mounting plate or table 28 and to be Ysecured thereby ininterlocked relation with the said mounting table 28, which for. use is placed on a slab 30 having oppositely disposed beveled recessesV 32 in its top surface which are adapted to be overlaid bythe fends of thermounting table 28.

unit 10 and hemispherical mounting 18 maybe lifted from the mounting table 28. The recessed under surface 22 of the mounting 18 Vfacilitates such separation by enabling a lifting implementV to be inserted more readily under the mounting 131than would be the case if the i under surface of the mounting were planar in character.

The mounting V18 carrying theprepare'd cornea 20 and the locking unit 10 thus may be removed from the t mounting tableZS,V and the mounting 1,8 with its prepared cornea thereon may be separated from the locking'unit l and to the preserving Vand dehydrating liquid. Many suitable synthetic plastic materials are available at trivial costs. Y f

I claim: i Y

1. A clamp for maintaining eye cornea in condition suitable for keratoplasty, comprising, in combination, a substantially hernispherical cornea-mounting element for receiving cornea free from Vsurface irregularities'and distortions, a removable locking elementincluding a central y opening adapted to Areceivefthe cornea-mounting element fand including oppositely disposed locking projections `directed inwardly with respect to the central opening-and In practice, a donor Vcornea whichv is to be used subsequently in forming a corneal graft, is applied smoothly to the hemisphericalV mounting 18, the undersurtzrce 22 of which is recessed to facilitate insertion of a lifting tool adapted to exert locking pressure Yon the corneafmounting clement and on a cornea mountedon theY element for maintaining the cornea `smoothly distributed over the mounting element, oppositely directed lockingingers on the locking element, a mountingtable,beneaththe lock- Ving element,'and meanson theimounting table cooperat- Y the mounting table.

for the mounting 18,V and the locking unit itl isY .applied over the hemispherical mounting which enters the ccnter opening 12, the unit i() being then pressed `down'- wardly untill opposite beveled ends 16 of ,the locking tongues or projections 14 tightly engage the cornea 2o,-

which thereby is maintained firmly on the mounting 18 and free from irregularities, wrinkles, folds,Y creases, or Y any other surface deformations VThe assembled cornean carryinghernispherical mounting 18 and the locking unit 1l) are appliedto the mounting table 28 and turned/with respect thereto until locking `fingers 24 Vengage under mounting table or plate 28 ,for the purpose of securing the cornea-carrying hemispherical mounting 18 andthe locking unit 10 in place on the mounting table 28; The

resultingv interlocked assembly now is ready for 'insertion into a vessel such as a test tube, containing anhydrous glycerine for effecting dehydration and preservation ot' the cornea 29 until the latterV is to be used.

The character of the assembly enablesready vretrieving thereof from the preserving andmdehydrating liquid, the

graft. For recovery, the assembly is placed on a slab 3Q withY the endsY ofV the mounting tableV VV2S overlying the beveled recesses 32 in the' top surface of the slabl 3.0,

I thereby enabling the locking nnit 10 to be rotated until'v the locking fingers 24 thereof clear the angular locking 1 lugs .26V on themounting table 2S, so that the.` lockingover the mounting element, oppositely-directcd locking the oppositely-directed locking lugs 26 provided on the intermediate the upstanding 2f. Aelamp for maintainingeyer cornea in condition suitable for keratoplasty, comprising, in combination, Va substantially hernispherical cornea-mounting `element for receiving cornea free from surface irregularities and distortions and having a recessedunder-'surface aremovable locking unit including anfopening. adapted to receive the cornea-mounting element andincluding oppositely disposed locking tongues directed inwardly with respect to the central opening and terminating in beveled locking surfaces adapted to exertlocking pressure ontheY cornea# mounting element and on a cornea mounted on the element for maintaining the cornea smoothly distributed securing the hemispherieal cornea-mounting unit and the locking unit in interloeked'relation with vrespect to each other and to the mounting table, the said locking lugs being frictionally engageable bythe lockngngers on the locking unit responsively to rotation ofthe locking unit until the locking fingers thereof 4engage the locking lugs angular Yanges, thereof and the mounting table. Y

l..l The clamp structure aslclairned in claim', inY corn# binaton with a supporting slab therefor having an upper surface provided with Oppsitely disposed beveled recesses Y adaptedto beY partially Yoverl-aid opposite endVv edges of the mounting table of the clamp structure, the said recesses facilitating separation Yof the'clarnp structure from Ihr Slab by enabling introductie@ ef lifting means beneath 8 n, the mounting table of the clamp structure for breaking adhesion between the mounting table and slab, the beveled recesses being similarly contoured in outwardly diminishing depth, and disposed with deepest portions in direct opposition toward each otherand similarly sloping up wardly to the upper surface of the slab, the beveled recesses being alignedly spaced apart at a distance conforming to the length of the mounting table of the clamping structure and being partially covered by opposite ends of the mounting table, the outwardly diminishing 10 depth of the recesses defining guides for facilitating insertion of a separating tool beneath the mounting table for eecting separation of the mounting table from the upper surface of the slab without disturbing relative 5 positions of parts of the clamp.

References Cited in the ile of this patent UNITED STATES PATENTS 378,449 Kendall Feb. 28, 1888 

